The present invention is directed to a device for processing a surface of an object, such as cleaning teeth, by means of directing water and a carrier gas containing an abrasive onto the surface being processed. The device includes a nozzle having a water channel terminating in a water discharge aperture and a separate carrier gas discharge aperture which is in communication with an arrangement for conveying the carrier gas with the abrasive from a source through the nozzle.
Devices, which direct water and a carrier gas containing an abrasive, are employed among other things for the elimination of plaque or for dulling dental bridges. Various materials come into consideration as the abrasive. Water-soluble materials, for example, sodium carbonate, have proven advantageous for prophylactic tooth treatment in the patient's mouth, for example, the removal of deposits from the teeth.
In a known device, a nozzle arrangement is situated at the free end of a handle and has a channel containing a carrier gas, which contains a dry abrasive or abradant, and a second separate channel containing water. These two channels discharge from separate discharge apertures with the water discharge channel having an aperture or series of apertures that concentrically surround the discharge aperture of the carrier gas and project so as to converge onto the stream of carrier gas. An example of this type of device is disclosed in U.S. Pat. No. 4,174,571.
Practice has shown on one hand that devices of this type have a tendency either for a blockage of the channels or for an encrustation of the channels to occur at the discharge location. This is particularly true when the discharge aperture inadvertently comes into contact with the processing surface such as the tooth. As a result of such contact, a backup occurs and a mixing of the dry abrasive with the water can occur before discharge from the nozzle. Such a mixing has a consequence that if particularly given long standstill times the abrasive cakes on the walls of the channels and apertures of the nozzle.
On the other hand, it has been shown that the erosive effect or respectively the cleansing effect in the known devices is not satisfactory when based upon appropriate gas and abrasive consumption which is not too high. In order to achieve a reasonable transport of the abrasive and in order to prevent blockage of the abrasive channel, a relatively large cross-section for both the channel and discharge aperture is required. Thus, it is only possible to achieve a satisfactory abrasive effect given the known device with a relatively high gas pressure and a large amount of gas or respectively with a greatly reduced abrasive additive given in a justifiable gas consumption. However, to provide a large amount of gas will result in a bulky arrangement which will impair the viewing of the processing surface as well as making it necessary to require an increase in the extraction of gas and fluid during the treatment of the mouth of the patient.